UBC Astronomers Discover The "Secret Powers" of White Dwarf Stars

The pretty picture above (courtesy of NASA, the European Space Agency and Harvey Richer) lies at the heart of an interesting discovery by a team of astronomers at UBC. Here’s an excerpt from the story in today’s paper:

UBC astronomers shed new light on the starsWhite dwarfs may not be as cold and inactive as scientists originally thought Chad SkeltonVancouver Sun In the life of a star, the white-dwarf stage is kind of like a long, boring retirement. After 10 billion years as a fiery sun — followed by a brief middle age as a red giant — the star collapses into nothing more than a small, dense core, slowly cooling off until the end of time. Or so it was thought. A couple of astronomers at the University of B.C. have discovered that, in the moment a star becomes a white dwarf, it somehow gets one last kick of real power — enough to send it hurtling through space at about 15,000 kilometres an hour. Harvey Richer, a professor at UBC, and PhD student Saul Davis made the discovery while analysing pictures of a globular star cluster taken by the Hubble space telescope. The two were trying to determine the age of the cluster, known as NGC 6397. But what struck them when they looked at the image was that all of the newborn white dwarf stars, regardless of their size, were near the outer edges of the cluster. On the surface, this made no sense to the astronomers. The gravitational field of a cluster slowly sorts stars by their mass, heavier stars near the centre and lighter ones farther out. If anything, you’d expect newborn white dwarfs to be closer to the centre, since that’s where they were when they were heavy red giants, and they haven’t had much time to go anywhere else. “The very young ones are not where they’re supposed to be,” Richer said. “They should be concentrated in the centre. And they’re not, which was a huge surprise.”